Process of making commutators



APPLICATION FILED MAY 2. I918.

Patented Sept. 28, 1920.

iii/673107;

UNITED STATES PATENT OFFICE.

SEBASTIAN N. SLOAN, OF TOLEDO, OHIO, ASSIGNOR,'BY MESNE ASSIGNMENTS, TO THE TOLEDO STANDARD COMMUTATOR (30., OF TOLEDO, OHIO, A CORPORATION OF OHIO.

PROCESS OF MAKING COMMUTATORS.

Specification of Letters Patent.

Patented Sept. 28, 1920.

Application filed May 2, 1918. Serial No. 232,087.

This invent-ion relates to a process of mak- 7 mg commutators for. dynamo electrlc machines, and has for its object to provide certain improvements by which tighter, more durable and otherwise more satisfactory commutators are obtained than is possible with the methods which have been used prior to this invention.

It is customary in the making of commutators to assemble the commutator segments on a suitable'segment holder or support between clamping rings or flanges, suitable insulation usually of mica being placed between the segments and also between the ends of the segments or tangs and the clamp ing rings, and at times also between the inner edges of the segments and the barrel or body of the segment supporting device.

After the parts are assembled the end clampmg rings or usually an integral flange at one end of the segment support, anda separate movable ring at the opposite end, are clamped against the segments to hold the parts together.

With the old methods. however, for a given size of commutator only a certain limited pressure could be applied through the end clamping rings. because of the dangerv of disrupting the construction due to lack of adequate support at the inner edges of the segments, and because of the liability of slippage of" the mica segments and mica rings separating the segments from the end clamping rings and the consequent short circuiting of the segments. Because of this limitation of permissible pressure with the old methods, the structure or commutator assembly could be tightened to a limited extent only, which is insuflicient to produce what I regard as the best commutators, for the reason that the segments can not be tightened sufficiently to prevent their becoming loosened in use, and some of the segments shifting from place. thus necessitating truing and other repairs.

By the improvements which I have conceived and have put into use very extensively with excellent results, I am enabled to subject the commutator assembly to tightening pressure far in excess of anything heretofore regarded as possible, or even contemplated by commutator manufacturers generally, and I thereby produce exceedingly tight commutators.

This is made possible by the herein described method, which includes the provision of an exceedingly hard insulating support between the inner edges of the seg- .ments and the segment supporting device which for convenience may be termed the spool. It includes also the application of pressure, both axially'and radially, at two difl'erent stages of the process, the final pressure which is applied after the hard insulating support is provided, being so powerful or severethat it is practically impossible for the commutator to become loosened or for the segments to shift from their proper positions. Additionally new steps of the process include a heat treatment of the assembly after theparts have been brought together in substantially their proper relative positions, but before. the final and severest pressure is applied, to bring about the proper hardening of the insulating material which it may be here stated is preferably bakelite, and also to bring about a certain flow and expansion of the insulating material to fill any'interstices which may have been left in the assembly after the latter has been subjected to the preliminary pressure or pressures.

The invention may be further brifly summarized as consisting in certain novel steps of the improved method which will be described in the specification, illustrated in the drawings as far as is necessary to convey a proper understanding of the invention, and set forth in the appended claims.

In the accompanying sheet of drawings, Figure 1 represents one desirable form of the spool or segment holding device which receives the segments and the insulating ma terial, the spool being shown in section; Fig. 9- is a similar view of a slightly different form of spool; Fig. 3 is a sectional view showing the manner in which the segments and insulating material are assembled before the end clamping rings or flanges are bent inward to permit the removal of the assembly ring which temporarily holds together the segments and intervening mica. Fig. 4 is a somewhat similar view when the spool of Fig. 2 is employed. Fig. 5 is a.

sectional view of a closing die inwhich the commutator assembly may be placed and subjected to variable degrees of axial and radial pressure including the final severe pressure above referred to, and Fig. '6 is a cross sectional view of one form of completed commutator made'in accordance with my invention.

In carrying out my process I prefer to use as a part of the commutator construction or assembly, a segment holder in the form of a spool 10, such as shown in Fig. 1, having a substantially cylindrical barrel 10 with integral segment clamping rings or flanges 10", or a spool such as shown-at 10 in Fig. 2, this spool likewise having clamping flanges 10 integral with the barrel but somewhat differently shaped. However, it is not essential to my invention that a segment holding spool be employed having. both clamping rings integral therewith, for it is common practice to employ a spool or segment holder with one integral end ring or clamping flange, and the other clamping ring separate from the spool and adapted to be pressed inwardly to produce the clamping pressure and to be locked in position by upsetting or peening the end of the barrel over this separate clamping'ring, or by meansof a clamping nut screwed onto the end'of the barrel or segment holder. I

have produced excellent results utilizing a.

segment holder or spool with one integral flange or clamping ring, and the other nonintegral, but I prefer to employ a form of segment holder wherein both end clamping means are integral, as previously stated.

In the preliminary steps of the process the commutator segments'll with the intervening insulating segments, usually of mica, are assembled in a suitable device which may be two separable halves of an assembling ring 12 and are placed around the barrel of the spool, together with the bands 13 and rings 14 of insulating material, usually of mica, the latter being employed as is well understood, to insulate the segments from the end clamping rings.

If segments of. the form shown in Fig. 4 are utilized, a spool 10, such as shown in Fig. 2, may be employed, 'in which event 7 there will be -no necessity for the mica bands 13, as will beobvious from an inspection of Fig. 4c.

As before stated, it is one of the features of the present invention that I provide an extremely hard insulating support for the inner edges of the segments in order that a permanently tight commutator may be formed, and in order that the severe pressure which I utilize may be applied and the slippage of mica prevented. To form this insulating support I prefer to use bakelite, although possibly other insulating materials which after being applied to the comsisting state by a baking process, after the parts of the commutator assembly have been placed in What I term a closing die and have been brought nearly to their final relative positions by a severe pressure, but in fact a moderate pressure compared to the final pressure which I utilize.

I have successfully applied the bakelite in two different ways, but possibly other 0 ways may suggest themselves to. one skilled in the art. I generally apply it in the form of a plastic strip, such as shown at 15 in F ig; 3, in which event the strip will be Wrapped around the barrel of the spool before the segments are placed around it whilesupported temporarily in the twopart assembling ring.

I have applied the bakelite also in a different manner and at a different point in 90 the process by first assembling the parts of the commutator and compressing them in the closing die and then forcing the bakelite through openings in the barrel of the spool into the annular space between the inner edges of the segments and the barrel, as will be more fully explained later.

l/Vhen the bakelite is applied in the manner first stated, 11. e., by wrapping a plastic strip 15 of the bakelite around the barrel of the spool, the parts are assembled in the relationship shown in Fig. 3, and the flanges of the spool are bent inwardly in a suitable press to a sufficient extent to hold the parts together and prevent the segments dropping out of place when the segment assembling ring 12 is removed.

Next the assembly is placed in a warming oven to increase the fluidity of the bakelite.

' Then the assembly is placed in what I term a closing die such as shown in Fig. 5. This closing die, which in itself forms no part of the present invention, so that only a brief description need be given,'ispreferably provided with a base 16, supporting a stationary die holder 17, which carries a lower stationary die 18, and itpreferably includes also an upper plunger 19 carrying an upper die 20. By these two dies 18 and on the end clamping flanges and radially on the segments, the axial pressure bendi wardly the end clamping flanges near y to their final positions. In this pressure applying step of the process a fairly severe pressure axially and radially is applied, but the pressure is not nearly as powerful or severe as that to which the assembly is later subjected. Sufiicient pressure is applied, however, to make all the parts snug. and to get the bakelite in place between the copper segments. and the spool. During this step of the process the bakelite is not in condition to act as a support for the segments. and the pressure must not be suflicient to disrupt the mica or bend the copper tangs. I might state, however, that to make clear the novelty of this process and the importance of an insulation such as bakelite capable of being hardened so that it can be utilized as an unyielding support for the segments, that the pressure to which the assembly is subjected in the step of the process just explained. may be several tons, and is usually as great as the maximum or final pressure to which commutators are subjected when made with the commonly employed and previously known processes.

It may be here stated that unless an absolutely correct amount of bakelite in strip form is placed about the barrel of the spool, one or more relief holes should be provided in the barrel so that the excess bakelite mav be extruded through the hole or holes while the pressure is applied in the closing die as above explained. I have found, however. that if a carefully measured or weighed amount of bakelite is wrapped around the barrel of the spool. a relief hole is not needed. Instead of utilizing a relief hole in the barrel, I may provide a relief opening or notch at the inner edge of each segment. these relief notches forming when the segments are assembled a continuous groove at the inner periphery of the segments contiguous to and joining the annular space between the inner edges of the segments and the outer surface of the spool barrel.

Next the commutator assembly is removed from the closing die and placed in a bakin oven where it is baked for a sutficient length of time and at the desired temperature to cause the bakelite to assume its exceedingly hard state. In this baking process the bakelite expands to some extent. and is frequently extruded at different points of the commutator, and this causes the bakelite to fill absolutely all interstices which may have remained unfilled after the assembly .was subjected to pressure in the ing all parts snug.

The commutator assembly is now ready for the final step of the process. It is next again placeed in .the closing die and subjected to radial pressure and to an exceedclosing die, ma-kvent movement or disruption of the mica,

and bending of the copper tangs. Preferably during this final application of pressure about the same, circumferential or radial pressure is applied, as was applied when the assembly was first placed in the closing die, but the axial pressure is safely increased to a point or value that would entirely wreck a commutator of the old type that did not have the advantage of the rigid bakelite support. To convey an idea of the pressures which are applied by my process and in the old processes when the assembly for a commutator of given size is first placed in the closing die, an axial pressure of four or five tons may be applied, which would be about the limit for a commutator .not having the hard bakelite support, and therefore about the limit of pressure to which commutators made by the old processes could be subjected. But went the commutator is placed in the closing die after the hardening process, it may be safely subjected to a pressure as great as twenty tons if the initial pressure was, say, four or five tons. Of course, the pressures to which a commutator is subjected in the closing die in the first and second pressure applying steps of the process will depend upon the size of the commutator, the pressures previousl mentioned being suitable for a very smal commutator, but for the larger commutators much heavier pressures are utilized. As an illustration, Imight state that truing and finishing steps.

When the bakelite is applied by the sec- 0nd method above referred to, the assembly is placed in a closing die with the annular space between the inner edges'of the segments and spool empty or unfilled, and pressure. is applied both axially and radially, forcing the parts to substantially their final positions. About. the same axial and radial pressures are used as when the assembly is first placed in the closing die in the rocess first explained wherein the bakelite is applied in the form of a plastic strip.

Next the bakelite in semi-fluid form is forced into the annular space between the spool by means of a press, the bakelite is segment holder into the annular space beforced through the openings in the barrel, filling the annular space between the inner edges of the segments and the barrel.

From this point the process is the same as that first explained, the assembly being next placed in a baking oven until the bakelite is thoroughly hardened, and expands so as to completely fill all interstices, and being then again placed in the closing die where the final and exceedingly severe pressures are applied radially and axially of the commutator, producing the finished product, ex-

cept for truing and finishing.

After the'bakelite is applied by forcing it through openings in the barrel of the tween the barrel and inner edges of the segments as above explained, the bakelite plug remaining in'the central shaft opening of the holder will, of course, be removed, and this can be done either before or after the bakelite is hardened, preferably after the baking process, in which event the plug will be bored out. I

Vhile I have explained the preferred way or ways of carrying out my process, I do not. wish to be confined to the precise steps explained, for they maybe modified, or certain of the steps omitted without a departure from the invention in its broadest aspects. For example, the manner in which the pressure is applied to the commutator assembly may be other than here shown, and while I prefer that pressure he applied both radially and axially, it is not essential that the pressuresbe applied simultaneously.

Furthermore, while I prefer, and regard it of considerable importance that the assembly be subjected to pressure both before and after the assembly is treated to produce the hard insulating support, nevertheless I regard it within the scope of my invention to omit the final pressure applying steps, 2'. e. to terminate the process with the baking step for the reason that. the provision of the hard-insulating support between the inner edges of the segments and the barrel of the segment holder in the baking step 'of the process causes the expansion of the bakelite and the filling of all interstices, and results in a commutator having decided advantages over those produced by the old methods. Furthermore, it is to be understood that I am not to be limited to the segment holders of the shape or type shown herein.

Having described my invention, I claim:

1. The process of making commutators which comprises assembling the segments on the barrel of a segment holder between end clamping rings, subjecting the segments to clamping pressure between the rings, providing between the segments and the barrel of the holder a hard pressure-resisting, 1nsulating support, and subjecting the segments to a second and increased pressure between the clamping rings.

2. The process of making commutators which comprises assembling the segments on the barrel of a segment holder between end clamping rings, applying pressure so as to bring the parts to substantially their final positions, treating the assembly so as to provide a hard insulating support for the inner edges of the segments, and then subjecting the segments to a further final clamping pressure between the rings.

3. The process of making commutators composed of segments, end clamping rings and an inner barrel or sleeve, which comprises providing between the sleeve and the inner edges of the segments a substantially unyielding insulating support, and applying pressure radially on the segments, and axially on the segments and end rings so as to force the latter tightly against the segments and the segments against said support.

4. The process of securing a tight commutator from an assembly composed of commutator segments, a segment holder including a barrel and end clamping rings with insulating material capable of being hardened between the segments and barrel, which comprises treating the assembly so as to cause the insulating material to form a substantially unyielding support for the inner edges of the segments and also to expand so as to fill interstices of the assembly, and subsequently causing an axial relative movement of the end clamping rings creating a severe clamping pressure on the segments.

5. The process of securing a tight commutator from a commutator assembly composed of segments and a segment support including a barrel and end clamping rings together with insulation capable of being hardened between the segments and the barrel, which comprises treating the assemblyso as to harden the insulating material and thereby provide a substantially unyielding insulating support for the inner edges of the segments, and then securing the parts the segments radially inward onto the support and at the same time causing an endwise relative movement between the rings j in permanently tight condition by pressing and a severe clamping pressure of the latter on the segments.

6. The process of making a tight commutator from an assembly composed of segments, a segment holder including a barrel and end clamping rings and a plastic insulating material between the barrel and inner edges of the'segments which comprises baking the assembly so as to cause said insulating material to harden, and subsequently clamping the segments tightly between the end rings.

7. The process of making a tight commutator from an assembly composed of a segment holder including a. barrel and end rings, segments arranged around the barrel and a plastic insulating material between the barrel and inner edges of the segments, which comprises baking the assembly so as to cause said insulating materialto harden and to expand so as to fill interstices, and

g the segments.

subsequently subjecting the segments to a radial pressure and the segments and end rings to a severe axial pressure.

8. The process of making commutators which comprises assembling the segments about a segment holder having a barrel and end clamping rings, subjecting the rings and segments to clamping pressure at two difi'erent stages of-the process and between the applications of pressure treating the assembly so as to provide between the inner edges of the segments and the barrel a substantially unyielding insulating support for 9. The process of making commutators which comprises assembling the segments about a segment holder having a barreland end clamping rings, then subjecting the rings and segments to clamping pressure at two difierent stages of the process and between the applications of pressure treating the assembly so as to'harden and cause an expansion of semi-plastic insulating material placed betweenthe inner edges of the segments and the barrel of the holder.

10. The process of making. commutators which comprises assembling the commutator segments about a holder composed of a barrel and end clamping rings, then sub-' jecting the segments and end rings-to pres-v sure whereby the parts-are brought sub lstantially to their final posi ions, then treatingthe assembly so as to c ause insulating material placed between the segments and barrel to become exceedingly hard, and then again subjecting the segments and end rings to pressure greater than that first applied.

11. The process of making commutators which comprises assembling commutator segments about a holder composed of a bar rel and end clamping rings,.then subjecting the assembly to radial and axial pressures whereby the parts are brought substantially to their final positions, then treating the assembly so as to cause insulating material placed between the segments and the barrel to become exceedingly hard, and then again subjecting the assembly to radial and axial pressure with the axial pressure increased over that first applied.

12. The process of making commutators which comprises assembling the segments about a holder composed of a barrel and end clamping rings with insulating material in plastic condition between the barrel and the inner edges of the segments, clamping the segments between the end rings, then treating the commutator so as to cause the insulating material to form a substantially unyielding support for the inner edges of the segments, and then subjecting the end rings and segments to severe clamping pressure.

13. The process of making a commutator which comprises assembling the segments about a holder composed of a barrel and end clamping rings with a strip of plastic insulating material between the barrel and inner edges of the segments, then after the end rings and segments have been brought to substantially their final positions subjecting the assembly to a baking process so as to cause thematerial to become exceedingly hard, and then subjecting the end rings and segments to severe clamping pres rial in substantially plastic condition but capable of being hardened placed between the barrel and segments, treating the as sembly so as to cause the material to become exceedingly hard and then ressing the end rings inwardly so as to rmly hold the segments and force the latter against the hard insulating material.

15. The process of making commutators of the type wherein the segments are clamped between and held in position by end clamping rings of the holder which comprises assembling the segments about the barrel of the holder, subjecting the assembly to pressure so as to cause the end rings to have a tight clamping action on the segments and the-segments to be pressed inwardly, then treating the assembly so as to cause insulating material placed between the segments and the barrel to become exceedingly hard, and then again subjecting the assembly to a final tightening pressure forcing the end rings inwardly toward the ends of the segments and tightly pressing the segments against said insulating ma terial.

16. The process of making commutators of the type wherein the segments are clamped between and held in position by end clamping rings or flanges of the segment holder which comprises assembling the segments about the barrel of the holder, providing a hard insulating medium between the inner edges of the segments and the barrel of the holder so as to prevent the slippage of insulation such as mlica. placed between the segments and between, the clamping rings or flanges and the segments and to support the segments against the clamping pressure of the end rings or flanges, and then pressing the end rings or flanges inwardly so as to firmly hold the segments and force the latter against the hard insulating medium.

17. The process of making commutators of the type wherein the segments are clamped between and held in position around the barrel of the segment holder by the pressure of end clamping rings or flanges which comprise assembling the segments around the barrel of the holder, treating the assembly so as to cause insulating material placed while in more or less plastic condition between the barrel and segments to become exceedingly hard and then subjecting the segments to tight clamping pressure by the end rings or flanges so that the latter will be pressed firmly against insulated surfaces of the segments and the segments will be clamped against said hard insulating material.

In testimony whereof, I hereunto aifix my signature.

SEBASTIAN N. SLOAN. 

